North Star Mine
Grass Valley, CA
The North Star Mine was the deepest mine in Grass Valley. It measured a vertical depth of 4000 feet. The location is now The North Star Mining Museum, part of the holdings of the Nevada County Historical Society. The museum is west of the Empire Mine and sits beside Wolf Creek at the south end of Mill Street by Hwy. 20.
"Monitor" for hydraulic mining.
The water would come in through the pipe on the ground. The rocks in the box are for counter balance. A "miner" would stand in that area and guide the monitor back and forth, directing the water against the hillsides washing it down to a big sluice box.